Ectaco SENCOR SDN 450 Uživatelský manuál stáhnout pdf (Strana 8)

EGE-Elektronik Spezial-Sensoren GmbH • http://www.ege-elektronik.com

1.08 E11011

Flow Sensors

Technique and application • Terminology

Detection Range

This is the range of flow rate within which a switching

point can be set at the amplifier. The setting ranges and

the temperature drift differ for various media. If not speci-

fied, the medium is water. At the borders of the detection

range, the temperature drift of the settingpoint will be sig-

nificantly higher.

Working range

The working range indicates the section of the detection

range for which the flow data is specified. At the outer

limits of the detection range, this data is reduced.

Nominal flow

For each sensor, data corresponding to its own nominal

flow is measured. This is nessesary because response

characteristic curves of sensors are non-linear.

Consequently the various sensor characteristics depend

on the location of the chosen operating point on the curve.

As a rule, the nominal flow-point is set in the middle of the

portion of the (simple logarithmic representation of the

characteristic) curve which appears to be linear. For this

operating point, the following values may be defined:

switching on and off times, stand by time, hysteresis and

temperature response.

Supply voltage

The supply voltage is the voltage range within EGE

Sensors function safely. For direct current supplies it

must be ensured that the limits are maintained even

including residual ripple.

Current consumption

The current consumption is the maximum value of the idle

current Io which the flow monitor draws without load.

Switching current

The switching current indicates the maximum continuous

current for the switching output of the device. For PNP

outputs this value applies to an ambient temperature of

25 °C. At higher temperatures the maximum switching

current is reduced. For devices with relays output the

value is related to the utility category AC-12 or DC-12 in

accordance with EN 60947-5-1.

Switching voltage

The switching voltage indicates the maximum voltage

(including residual ripple) to be switched with the relay

output.

Switching power

The switching power indicates the maximum power to be

placed on the output relays.

Ambient temperature

The ambient temperature indicates the maximum and

minimum permissible temperatures for the sensor.

Temperature medium

The temperature range for which a sensor is rated. Applies

to the medium to be monitored.

Temperature gradient

The change of the medium´s temperature within a defined

period of time is called temperature gradient. EGE sensors

have a temperature gradient up to 250 K/min. for water. If

the change of medium temperature exceeds this value,

there will be a malfunction of the flow controller.

Start-up time

The start-up time is the period of time required by the flow

detector to reach a stable state after the operating voltage

has been switched on. Prerequisite is that the medium

flows at the rated velocity and that the sensor has adapted

to the temperature of the medium before switching the

supply voltage on. The start-up time is prolonged in a

static medium and reduced if the medium flows faster

than the rated value.

Reaction time

The reaction time combines the switch-on and -off time.

Switch-on time elapses from the beginning of the flow

until the switching point set at the amplifier is reached.

Switch-off time characteristic results for the flow sensors

at pump shut-down. If the set switching point is close to

maximum flow, the time elapsing between the pump shut-

down and the indication of the flow decrease is short. If

the switching point is close to the static value, the off-

transition time will be long.

Compressive strength

Pressure resistance relates to the sensor casing. Standard

models with metal casings will withstand pressures as

high as 100 bar. Up to the indicated maximum pressure,

the sensor provides a steady signal and the casing suffers

no damage.

Protection

The protective system indicates the protection of the sen-

sors against penetration of foreign bodies and water

according to EN 60529

Delay

The variable time delay which can be set between 0 and

25 seconds becomes active during flow standstill (drop-

out delay). If the medium ceases to flow and the amplifier

display indicates this state, the relay contact is actuated

only after the set delay. During the delay period the yellow

LED lights up together with the red LED.

Cable break monitoring

Cable break monitoring shuts off the flow monitor output

if no sensor is connected or if the sensor cable has been

severed. In case of cable severing, "flow failure" signal is

displayed.

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